More fixes for relative urls when running Grafana under a different sub path (#10470)

* Add nginx proxy docker container

Ease test/verification of running Grafana thru a reverse proxy

* Add apache proxy docker container

Ease test/verification of running Grafana thru a reverse proxy

* Fix relative urls for reset password page

* Fix relative urls for signup page

* Fix relative urls for login page

* Fix relative urls edit plugin page

docker/blocks/apache_proxy/Dockerfile

@@ -0,0 +1,4 @@
+FROM jmferrer/apache2-reverse-proxy:latest
+
+COPY ports.conf /etc/apache2/sites-enabled
+COPY proxy.conf /etc/apache2/sites-enabled

docker/blocks/apache_proxy/docker-compose.yaml

@@ -0,0 +1,9 @@
+# This will proxy all requests for http://localhost:10081/grafana/ to
+# http://localhost:3000 (Grafana running locally)
+#
+# Please note that you'll need to change the root_url in the Grafana configuration:
+# root_url = %(protocol)s://%(domain)s:/grafana/
+
+  apacheproxy:
+    build: blocks/apache_proxy
+    network_mode: host

docker/blocks/apache_proxy/ports.conf

@@ -0,0 +1 @@
+Listen 10081

docker/blocks/apache_proxy/proxy.conf

@@ -0,0 +1,4 @@
+<VirtualHost *:10081>
+    ProxyPass /grafana/ http://localhost:3000/
+    ProxyPassReverse /grafana/ http://localhost:3000/
+</VirtualHost>